Impact line printers use an endless type band which is impacted by print hammers arranged in a row. The band is commonly made of metal such as steel on which a row of raised characters and timing marks have been formed on one side. The drive system for revolving the metal band commonly comprises a pair of pulleys one of which is the drive pulley and the other an idler pulley. The band is trained around the pulleys in tension with the reverse side of the band in contact with the pulley so as to be driven by friction. It is customary to provide a platen of metal or other hard material behind the band in the areas between the pulleys as backup to the band. A flat surface of the platen engages the band at all times. The continuous sliding contact of the type band on the platen punctuated by the frequent impacts of the hammer causes the band and platen to wear to the point where one or both must be replaced. Various wear prevention means have been provided to reduce or eliminate the wear. Among these is a wear prevention layer or strip bonded to the face of the platen. Usually the material is one that has low friction properties and is resistant to deformation by impact. One such material used on printers such as the IBM 6262 Printer is a polymer. In such printers it is customary to operate the band drive at speeds of 100-700 inches per second.
In printers using such a platen, a problem with the band drive motor develops after a period of time where the motor current required to maintain band speed constant at the desired level increases to the point where the motor becomes overheated and reliability and safety elements of the printer controls terminate printer operation. It was determined that the motor problem was due to the increased loading on the drive motor by the band. It was discovered that the increased loading was due to increased frictional drag brought about by the wear and polishing of the wear strip as a consequence of the sliding engagement of band and the strip. The problem has been observed at band speeds as low as 120 inches per second and occurs even where lubricant such as PTFE is applied to the band platen interface.